Transcript Star Life Cycles Stellar Nebula

Star Life Cycles
Stellar Nebula
Stars begin life as
cloud of gas + dust
Cloud condenses
and becomes more
massive
Nuclear fusion
begins (the power
source of stars)
H + H -> He
Proto-star (Embryonic star)
Stellar Nebula
continues to
collapse under its
own weight
star grows more
massive
Main Sequence Star
In this stage, the
outward pressure of
fusion (energy) and
inward pressure of
gravity are balanced
Star spends more
than 90% of its life
Our sun is in this
stage
Variable Star
Star undergoes
variations in
luminosity
(brightness)
because the forces
are becoming
unbalanced
Red Giant
As core runs out of
H, nuclear fusion
stops
Outer shell of star
pushes outward, H
gas cools and glows
red
Core condenses due
to gravity and He
fuses into C
If Star is Small…
Core continues to
collapse
Outer portions of
star are expelled,
forming a planetary
nebula
Small star, continued
 As planetary nebula
expands, remaining
core glows white, but is
much smaller than
original star
 White Dwarf
 (Becomes black dwarf
once core cools)
Supernova
Star runs out of fuel,
and force of gravity
starts to condense
remaining material
Incredible inward
force restarts
nuclear fusion,
causing an
incredible explosion
Supernova Remnant
After explosion, an
ever-expanding
shock wave spreads
out.
Cloud of debris and
other stellar material
is seen expanding
from explosion
Black Hole…
After explosion, star
material can become
so dense that all
material, even light,
can collapse into an
infinitely small space
…or, a Neutron Star
If not as much mass
remains, the leftover material can recondense and
become a star again
Much smaller and
less bright than
parent star
The Cycle
Another View of the Cycle
Annndd…..yet one more